powerpc: Use generic idle loop

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Link: http://lkml.kernel.org/r/20130321215235.026838003@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/powerpc/Kconfig

@@ -133,6 +133,7 @@ config PPC
 	select HAVE_ARCH_JUMP_LABEL
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select GENERIC_SMP_IDLE_THREAD
+	select GENERIC_IDLE_LOOP
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_TIME_VSYSCALL_OLD
 	select GENERIC_CLOCKEVENTS

arch/powerpc/kernel/idle.c

@@ -33,11 +33,6 @@
 #include <asm/runlatch.h>
 #include <asm/smp.h>
 
-#ifdef CONFIG_HOTPLUG_CPU
-#define cpu_should_die()	cpu_is_offline(smp_processor_id())
-#else
-#define cpu_should_die()	0
-#endif
 
 unsigned long cpuidle_disable = IDLE_NO_OVERRIDE;
 EXPORT_SYMBOL(cpuidle_disable);
@@ -50,45 +45,28 @@ static int __init powersave_off(char *arg)
 }
 __setup("powersave=off", powersave_off);
 
-/*
- * The body of the idle task.
- */
-void cpu_idle(void)
+#ifdef CONFIG_HOTPLUG_CPU
+void arch_cpu_idle_dead(void)
 {
-	set_thread_flag(TIF_POLLING_NRFLAG);
-	while (1) {
-		tick_nohz_idle_enter();
-		rcu_idle_enter();
+	sched_preempt_enable_no_resched();
+	cpu_die();
+}
+#endif
 
-		while (!need_resched() && !cpu_should_die()) {
+void arch_cpu_idle(void)
+{
 	ppc64_runlatch_off();
 
 	if (ppc_md.power_save) {
-				clear_thread_flag(TIF_POLLING_NRFLAG);
-				/*
-				 * smp_mb is so clearing of TIF_POLLING_NRFLAG
-				 * is ordered w.r.t. need_resched() test.
-				 */
-				smp_mb();
-				local_irq_disable();
-
-				/* Don't trace irqs off for idle */
-				stop_critical_timings();
-
-				/* check again after disabling irqs */
-				if (!need_resched() && !cpu_should_die())
 		ppc_md.power_save();
-
-				start_critical_timings();
-
-				/* Some power_save functions return with
+		/*
+		 * Some power_save functions return with
 		 * interrupts enabled, some don't.
 		 */
 		if (irqs_disabled())
 			local_irq_enable();
-				set_thread_flag(TIF_POLLING_NRFLAG);
-
 	} else {
+		local_irq_enable();
 		/*
 		 * Go into low thread priority and possibly
 		 * low power mode.
@@ -96,18 +74,9 @@ void cpu_idle(void)
 		HMT_low();
 		HMT_very_low();
 	}
-		}
 
 	HMT_medium();
 	ppc64_runlatch_on();
-		rcu_idle_exit();
-		tick_nohz_idle_exit();
-		if (cpu_should_die()) {
-			sched_preempt_enable_no_resched();
-			cpu_die();
-		}
-		schedule_preempt_disabled();
-	}
 }
 
 int powersave_nap;

arch/powerpc/kernel/smp.c

@@ -669,7 +669,7 @@ __cpuinit void start_secondary(void *unused)
 
 	local_irq_enable();
 
-	cpu_idle();
+	cpu_startup_entry(CPUHP_ONLINE);
 
 	BUG();
 }